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W. C. STEVENS AND N. L. MORTENSEN.

MOTOR CONTROLLER. APPLICAHON .FILED NOV. 30. 191

Patented 001. 14, 1919.

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iv mamas W. .C. STEVENS AND N. L. MORTENSEN.

MOTOR CONTROLLER.

APPLICATION FILED NOV. 30. 19M.

1,318,620. Patented Oct. 14,1919.

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Q Mnnnnnnnnnnnm HUB IV UNITED STATES PATENT OFFICE.

2 WILLIAM c. srsvnns, or summrr, new Jnasniz, Ann NIELS L. uon'rnnsnu, or r MILWAUKEE, WISCONSIN.

moron-commune.

Specification of Letters Patent.

Patented Oct. 14, 1919.

'Applieation filed November 30,1914. Serial No. 874.687.

To all whomt't may concern Be it known that we, WILLIAM C. STEVENS and Nnzns L, MORTENSEN, the former a citi zen of'the United States, residing at Summit, in the county of Union and State of New Jersey, and the latter a'subject of the of motor operated hoists and other variable load apparatus. j 1

As is well understood where a motor driven machine must be slowed down to a predetermined speed or slowed down and stopped in a. given position or within a definite period of time, variations in the load on the driving motor tend to distort the deceleration curve and to produce very undesirable resultsyand this invention has,

among its objects to minimize the aforesaid tendencies of load variations. In other words, the invention aims to produce a substantially uniform deceleration. irrespective of load conditions. j

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate two embodiments of the invention, which will now be described, it of course being understood that the invention is not limited to the specific forms thereof chosen for purposeof illustration.

In the accompanying drawing, Figure 1- shows diagrammatically a controller for direct current motors; and,

Fig. 2 shows diagrammatically a controller for alternating current motors' Briefly set forth, Fig. l'shows a'shunt the motor M having a series resistance 'r and an armature shunt resistance 1', both of said resistances being connected in circuit for slow down and the resistance 9* being grade ually decreased slow down efiect thereof. In addition, means are provided whereby the armature shunt resistance is regulated in accordance with both the speed of the controlled motor automatically to increase the and the position. of the driven machine to compensate for theefl'ect of load variations. Inother words, the aforesaid means effects varlation of the shunt resistance for deceleration according to the load conditions and also limits the rate'of deceleration irrespective of load conditions whereby the uniformity of slow-down under varying loads is greatly. improved.

More specifically referring to the drawing, the resistance 1' is divided into sections and provided with a series of control switches 1, 2 and 3 by means of which it may be used for startingas well as slow down purposes, I

said switches being of any preferred type and controlled in any desired manner. .In accordance with the-usual practice the resistance 1' would be reinserted in circuit prior to the inclusion of the shunt resistance T, but of course it might be utilized in any other preferred way.

The aforesaid automatic controlling means for the shunt resistance 7'' includes an electro-responsive switch a controlling the continuity of the circuit of said resistance, an

adjustable controlling element 5 of the cross head type for varying said resistance, a shunt wound pilot motor 6 for operating said adjustable element, electroresponsive reversing switches 7 and 8 controlling the pilot motor 6 and a reverse current relay 9 controlling said switches 7 and 8. The circuit of the switches 17 and 8 is also controlled by the switch 4, that is to the extent of deenergizing both when thearmature. shunt is open.

The reverse current relay 9 has-its operatin winding 9 connected in a Wheats-tone ridge including the motor armature A, the resistance r, a fixed resistance 10 and a variable resistance 11. More specifically,

the motor armature A and resistance r are connected in series across the line L-L while the resistances 10 and 11 are likewise connected in series across the line and the winding of relay 9 connected on one side to the controlling arm 12 of resistance 11 and between the motor armature A and resistance r on its other side. Thus it will be observed that with the Wheats'toiie brid e balanced, the relay 9 would be inert, w; ereas upon unbalancing thereof its armature would be deflected in opposite directions according to the direction of current through the winding 9!.

\Vhen the relay attracts its armature to the right it tends to energize switch 7, whereas upon attracting its z'trmature to the left it tends to energize switch 8, thus providing for reverse movement of the motor operated resistance varying element 5. Further, as will be apparent, the relay will be caused to act' upon variations in the speed of the motor M and will thus tend to effect regulation of the armature shunt. resistance to a certain extent in accordanc with the load on the motor. However, with the means thus far described provision would only be made for one slow speed setting, namely, that ultimately desired, so that while under varying load conditions the motor would be slowed down to the desired degree within a given period the deceleration curve might nevertheless be subject to wide and objectionable deviations but. such conditions are rectified by the variable resistance 11.

The arm 12 governing the resistance 11 is biased, as by means of a spring 13, to the position illustrated and is adapted to be moved to the left in synchronism with the driven n'lachine for slow down, so that during a given period its position will always correspond to that of said machine. Such operation of the rheostat may be eitected in various different ways, as for example, by the traveling nut 14, schematically illustrated. The nut 14; is shown as mounted upon a screw-threaded shaft 15 designed to be operatively connected either directly to the motor M or to the driven machine, the arrangement being such that the nut 14 engages and moves the lever 12 only during the slow-clown period. Also in conjunction with the mechanism ust described, a switch 16 is provided to control the operating winding 4 of switch 4:. The switch 16 is biased to closed position to energize the switch 4 and thus efi'ect completion of the armature shunt circuit, whereas it is normally retained in open position by the resistance controlling arm 12 and is released only when said arm is moved by the traveling nut.

Thus it will be observed that the switch 16 may be released in any pre-selected position of the driven mechanism to effect connection of the armature shunt resistance and to render the switches 7, 8 responsive to the reverse current relay. Further, it will be observed that the position of the resistance controlling arm 12 will through its effect on the relay establish a limit to the speed reduction of the motor M and that as said arm is moved by the traveling nut it will vary said limit in accordance witlr the position of the driven mechanism. Thus, inasmuch as the relay is also governed to a certain extent by the speed of the motor M, it will be apparent that said relay under the combined influence of the motor speed and ot' the variable resistance 11 will tend to establish a plurality of distinct and progressively decreasing speeds corresponding to the position of the driven mechanism so that even where wide variations in load are encountered the deviations from the desired slow-down curve may be confined within narrow limits. More specifically considering the operation of the controller the position of the controlling arm 12 determines the electrical balancing conditions of the VVheatstone bridge while the relay responds during and in accordance with the character of unbalanced conditions to cause operation of the motor driven element to decrease or increase the armature shunt resistance as may be required to restore balanced conditions in the \Vheatstone bridge.

Although the connections are very simple and obvious the same will be briefly set forth. The armature A and field winding F of the motor M are connected directly across lines L and L, the former through resistance R and a suitable control switch 17. Likewise the field f of the pilot motor is connected directly across lines L and L. while the armature circuit of said motor may be traced as follows: Vith switch 7 energized circuit extends from line L by conductor 18 through the lower set of contacts 8 of switch 8, by conductor 19 through the motor armature a from right to left, by conductor 20 through the upper set of contacts 7* of switch 7, by conductor 21 through the lower set of contacts 4 of switch l. by conductors 22 and 23 to line L. On the other hand, with switch 8 energized circuit extends from line L by conductor 18 through the lower contacts 7 of switch 7, by con ductor 20 through the armature a from left to right, by conductor 19 through the upper set of contacts 8 of switch 8. to conductor 21 and thence to line L as already traced. The energizing circuit of switch 7 may be traced from line L by conductors 18 and 24 through the relay and its contacts 9", by eon ductor 25 through the winding 7" of said switch to conductor 21 and thence to line L, as already traced, while the energizing circuit of switch 8 may be traced from conductor 24 through the relay and its cont-act 9 by conductor 26 through the winding 8 of switch 8 to conductor 21. The energizing circuit of switch et extends from line L by conductors 18, 24 and 27 through switch 16. by conductor 28 through the winding 4-" of switch 4 by conductor 29 to line L.

Referring now to Fig. 2 the same shows an alternating current motor M having a stator winding S supplied with current from lines 30, 31 and 32 and a rotor winding R having in circuit therewith regulating resistances 33. 34. and 35. The resistances 33, 34 and 35 are controlled by a movable element 36 operated by a direct current pilot motor 6, like that illustrated in Fig. 1, and having similar control switches 7 and 8. The control switches 7 and S are in turn governed by a reverse current relay 9, like that shown in Fig. 1. In this instance, however, the reverse current relay is connected in circuit between two. buckinggenerators 37 and 38, both provided with armatures a and shunt fields f and one having its armature operatively connected to the rotor of the main motor M while the other has its armature operatively connected to and driven by a constant speed alternating current motor 39 connected to the source 30, 31 32.

The relay 9 is so connected in circuit as to respond in one direction or the other according to which of the generators predominates and this in turn will be governed by the speed of the main motor M. In consequence the means thus far described provides for the same control of the pilot motor operated rheostat as the Wheatstone bridge arrangement shown in Fig. 1. Moreover, in the arrangement shown in Fig. 2 a resistance 40 is connected across the armature of the generator 37 with an adjustable tap 41 connected to the winding 9 of relay 9 and therethrough to the armature of the generator 38, and, as will be apparent, this means provides for accomplishment of substantially the same regulation as the adjustable resistance in the Wheatstone bridge arrangement of Fig. 1. Thus, with the tap 41 of the resistance 40 operated in a similar manner to the arm 12'of Fig. 1 the motor M will be controlled as already described.

What we claim as new and desire to se cure by Letters Patent is 1. In a controller for decelerating a motor operating under varying load conditions, in combination, electro-responsive means affording regulation of the speed of the motor substantially independent of load variations and means controlling the former means to effect substantially uniform deceleration of the motor thereby irrespective of load conditions.

2. In a controller for decelerating a motor operating under varying load conditions, in combination, electro-responsive means affording regulation of the speed of the motor substantially independent of the load variations and automatic means controlling the former means to effect deceleration therebyin a step by step manner for substantially uniform deceleration of the motor irrespective of load conditions.

3. In combination, a motor operating un der variable load conditions, speed regulating means therefor including a normally open armature shunt and resistance therefor and automatic means to close said shunt for deceleration of the motor and for regulating said resistance for substantially uniform decele'ration of said motor irrespective of load conditions. I

4:. In combination, a motor operating under variable load conditions, normally inert means operable to decelerate said motor and automatic means for rendering the former means effective and controlling the operation thereof to effect substantially uniform deceleration of the motor under varying load conditions.

5. In combination, a motor, e1ectro-re sponsive decelerating means therefor and control means for the former means including a. device operable by and in synchronism with said motor for effecting substantially uniform deceleration of said motor irrespective of load conditions.

6. In combination, a motor operating under varying loads, speed varying means, a polarized relay controlling said means, means for subjecting said polarized relay to the influence of thespeed of said motor and means also subjecting said polarized relay to the influence of the degree of operation of said motor.

7. In combination, a motor operating under varying loads, means including a polarized relay affording regulation of the speed of said motor substantially independent of load variations and means operating in synchronism with said motor to effect deceleration of said motor by the former means and to insure substantially uniform deceleration irrespective of load conditions.

8. In combination, a motor operating under varying load conditions. means including a reverse current relay affording regulation of the speed of said motor substantially independent of load variations and means acting upon said relay to establisha definite relation between the rate of deceleration of the motor and the number of revolutions of said motor during the period of deceleration.

9. In combination, a motor operating under varying load conditions, decelerating means therefor including a reverse current relay, means subjecting said relay to the influence of the speed of the motor and means also subjecting said relay to the influence of the number of revolutions of said motor during deceleration for the purpose set forth.

10. In a controller for a motor operating under varying load conditions, in combination, automatic decelerating means and means limiting the rate of deceleration of said former means irrespective of load condit'ions, the operation of said first mentioned means being dependent upon said second mentioned means.

11. In a controller for a motor operating under varying load conditions,.in combina tion, decelerating means, means independent of load conditions for automatically varying the range. of effectiveness of said first mentioned means to effect deceleration substantially independent of load conditions and means controlled by said second mentioned means for normally rendering said decelerating means inert.

12. In combination, a motor, a shunt resistance and a series resistance to be included in circuit with said motor for deceleration thereof, means for varying said shunt resistance, a polarized relay subjected to influence in accordance with load variations for governing the action of said means to compensate for such variations and means operable in synchronism with the motor during deceleration thereof for varying the action of said relay.

1 8. In combination, a motor, a shunt resistance and a series resistance for the circuit thereof, means for varying said shunt resistance, a polarized relay connected in a Wheatstone bridge between said shunt and series resistances for governing the action of said means to compensate for variations in load upon the motor for rendering the speed thereof substantially independent of such variations, and means operable in synchronism with the motor for varying the action of said relay.

14. In combination, a motor, a normally open resistance shunt and a series resistance forthe circuit thereof, means for varying the resistance of saidv shunt, means for governing the action of said former means to compensate for variations in load upon the motor, said latter means including a polarized relay subjected to influence in accordance with the value of such load and also including means operable in synchronism with the motor during deceleration thereof for closing said resistance shunt and for varying the action of said relay.

15. In combination, a motor, a shunt resistance and a series resistance for the circuit thereof, normally inert means for varying said shunt resistance, means for governing the action of said former means to compensate for variations in load upon said motor, said latter means including a polarized relay subjected to influence in accordance with the value of such load and also including means to operate in synchronism with the motor during deceleration thereof for rendering said resistance varying means operative and for modifying the action of said relay thereupon.

In witness whereof, We have each hereunto subscribed our names in the presence of two witnesses.

WILLIAM C. STEVENS. Witnesses:

T. D. MONTGOMERY, LAURA E. SMITH.

NIELS L. MORTENSEN.

Witnesses:

TEKLA BAs'r, H. WA'rsoN. 

